dmaengine: altera-msgdma: Fix struct documentation blocks

dmaengine: altera-msgdma: Fix struct documentation blocks

Fix some misspelling/description issues, demote non-kerneldoc header
to standard comment block and provide a new description for
msgdma_desc_config()'s 'stride' parameter.

Fixes the following W=1 kernel build warning(s):

 drivers/dma/altera-msgdma.c:163: warning: Function parameter or member 'node' not described in 'msgdma_sw_desc'
 drivers/dma/altera-msgdma.c:163: warning: Function parameter or member 'tx_list' not described in 'msgdma_sw_desc'
 drivers/dma/altera-msgdma.c:197: warning: Function parameter or member 'lock' not described in 'msgdma_device'
 drivers/dma/altera-msgdma.c:197: warning: Function parameter or member 'dev' not described in 'msgdma_device'
 drivers/dma/altera-msgdma.c:197: warning: Function parameter or member 'irq_tasklet' not described in 'msgdma_device'
 drivers/dma/altera-msgdma.c:197: warning: Function parameter or member 'pending_list' not described in 'msgdma_device'
 drivers/dma/altera-msgdma.c:197: warning: Function parameter or member 'free_list' not described in 'msgdma_device'
 drivers/dma/altera-msgdma.c:197: warning: Function parameter or member 'active_list' not described in 'msgdma_device'
 drivers/dma/altera-msgdma.c:197: warning: Function parameter or member 'done_list' not described in 'msgdma_device'
 drivers/dma/altera-msgdma.c:197: warning: Function parameter or member 'desc_free_cnt' not described in 'msgdma_device'
 drivers/dma/altera-msgdma.c:197: warning: Function parameter or member 'idle' not described in 'msgdma_device'
 drivers/dma/altera-msgdma.c:197: warning: Function parameter or member 'dmadev' not described in 'msgdma_device'
 drivers/dma/altera-msgdma.c:197: warning: Function parameter or member 'dmachan' not described in 'msgdma_device'
 drivers/dma/altera-msgdma.c:197: warning: Function parameter or member 'hw_desq' not described in 'msgdma_device'
 drivers/dma/altera-msgdma.c:197: warning: Function parameter or member 'sw_desq' not described in 'msgdma_device'
 drivers/dma/altera-msgdma.c:197: warning: Function parameter or member 'npendings' not described in 'msgdma_device'
 drivers/dma/altera-msgdma.c:197: warning: Function parameter or member 'slave_cfg' not described in 'msgdma_device'
 drivers/dma/altera-msgdma.c:197: warning: Function parameter or member 'irq' not described in 'msgdma_device'
 drivers/dma/altera-msgdma.c:197: warning: Function parameter or member 'csr' not described in 'msgdma_device'
 drivers/dma/altera-msgdma.c:197: warning: Function parameter or member 'desc' not described in 'msgdma_device'
 drivers/dma/altera-msgdma.c:197: warning: Function parameter or member 'resp' not described in 'msgdma_device'
 drivers/dma/altera-msgdma.c:265: warning: Function parameter or member 'stride' not described in 'msgdma_desc_config'

Signed-off-by: Lee Jones <lee.jones@linaro.org>
Cc: Stefan Roese <sr@denx.de>
Link: https://lore.kernel.org/r/20200714111546.1755231-8-lee.jones@linaro.org
Signed-off-by: Vinod Koul <vkoul@kernel.org>